Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
AVFormatParameters are converted into corresponding private options in
av_open_input_file/stream() compat wrappers, so accessing them from
demuxers is redundant.
The variable is used for containing the parsed value of framerate,
using a lexically consistent name eases readability/understanding.
Signed-off-by: Anton Khirnov <anton@khirnov.net>
AVERROR(ENOMEM).
AVERROR_NOMEM is deprecated and will be dropped at the next libavutil
major bump.
Originally committed as revision 22791 to svn://svn.ffmpeg.org/ffmpeg/trunk
- Verbose debug information is at max -v 9 now;
- Add an empty space for readability.
Originally committed as revision 19541 to svn://svn.ffmpeg.org/ffmpeg/trunk
patch by Stefano Sabatini, stefano.sabatini-lala poste.it
along with some spelling/consistency fixes for the long names by me
Originally committed as revision 13649 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diego Biurrun
Anton Khirnov
Luca Barbato
Vittorio Giovara
Martin Storsjö
Stefano Sabatini
Mans Rullgard
Diego Elio Pettenò
Ramiro Polla
Nash Tsai
kemuri
Aurelien Jacobs
Baptiste Coudurier